Flexing their new power to determine the Democratic presidential nomination, a bloc of Ohio superdelegates is withholding endorsements from Barack Obama and Hillary Rodham Clinton until one or the other offers a concrete proposal to protect American jobs, two Ohio Democrats told Politico Wednesday.

The apparent deal among Ohioans is the first evidence of superdelegates’ banding together and seeking concessions from the presidential candidates in return for votes at the convention. It’s a practice that could become more common after Clinton’s victories in Ohio and Texas on Tuesday put her back on solid footing in her race against Obama and ensured that the battle for superdelegates will continue for many weeks to come.

Ohio Democratic Rep. Marcy Kaptur, one of the leading protectionists in Congress, said Ohioans have many suggestions on economic and trade issues they hoped the candidates would address.

“We have a laundry list of measures we think would be effective, some involving tax policy, some involving investment policy, intellectual property incentives to hold investments in this country,” Kaptur said. “I’m hoping superdelegates [who] are uncommitted that have the economy as their major concern will gravitate to our group and use that power to gain additional attention.”

“We had a general agreement,” Kucinich said of the pact. “We have economic issues that need to be addressed. Ohio has economic issues more urgent than any other state.”

A spokesman for Ryan acknowledged that the Ohioans sent a letter to both Obama and Clinton last week in which they outlined their views about the economy, but he insisted there was no agreement to withhold votes. Ryan himself told Politico: “We want the candidates to talk about the issues important to Ohio. We all have the same issues, and we’ve talked about them. But I don’t think there’s any coordinated effort to stick together. There are conversations. It gets hard to build any kind of alliance when, in a lot of our districts, certain candidates did really, really well.”

Ryan said he had been thinking of making an endorsement “up until Monday,” then added: “There’s always talk of trying to build coalitions.”

In the Feb. 25 letter, the Ohio lawmakers urged the candidates to address manufacturing job losses, “unfair” international competition and U.S. trade policy, with a particular emphasis on China. “American workers and industry can compete with any nation, provided the playing field is even,” they wrote.

The Ohio superdelegates’ decision to remain uncommitted even after their state had spoken mirrored patterns seen across the country Wednesday. Only two superdelegates — Dayton Mayor Rhine McLin and Georgia Democratic Party Chairwoman Jane Kidd — changed their positions after Clinton won in Texas, Ohio and Rhode Island, and both of them endorsed Obama.

Harold Ickes, a senior adviser to the Clinton campaign, said on a conference call Wednesday that many superdelegates were “keeping their powder dry. … They’re watching and waiting.”

Democratic officials said Tuesday that the Obama campaign planned to unveil the support of 50 new superdelegates Wednesday. No such announcement came Wednesday, but several Obama backers said that such a plan had, in fact, been in the works. Rep. Jan Schakowsky (D-Ill.) said Wednesday morning that she thought the plan was “going forward” but added that she had yet to check in with the campaign.

Both campaigns had expected that Wednesday would bring a wave of new endorsements for Obama if he’d won in both Texas and Ohio.

“Many people [backing Clinton] were saying, ‘I’m going to go on and pull out after Tuesday.’ And now they’re saying, ‘Under no circumstances am I pulling out. I’ve been there all along,’” said Clinton supporter Rep. Emanuel Cleaver II (D-Mo.). “It’s amazing how three wins can turn people around.”

Clinton’s victories provided much-needed relief for her backers on Capitol Hill, especially African-Americans who had faced pressure from some black activists to back Obama.

As Clinton gave her victory speech in Ohio Tuesday night, a group of her congressional supporters gathered around a television at the home of Rep. Maxine Waters (D-Calif.). As Clinton ran through a list of those who had helped her in Ohio — the governor, the lieutenant governor, former Sen. John Glenn — they anxiously yelled at the television, “And? And?”

Perhaps more than any other African-American in Congress, Tubbs Jones had gone out on a limb to support Clinton, serving as national co-chairwoman of her campaign.

“The senator is well aware of what some African-American supporters have experienced,” said Cleaver, who was pleased that Clinton had recognized Tubbs Jones. “For people like Stephanie Tubbs Jones and [Rep.] Sheila Jackson Lee [D-Texas], this has been a vindication for them, because they have really taken hits for supporting Sen. Clinton. Today, they’re looking pretty good.”

The next big contest in the presidential race is Pennsylvania, and it’s seven weeks away.

Superdelegates from the Keystone State were almost bemused Wednesday that the state was now being described as “the new Iowa” because of the time the candidates would spend campaigning there and the significance of the outcome.

“I never expected to be in a position where Pennsylvania was going to matter,” said Rep. Jason Altmire (D-Pa.). Altmire said he feared that the campaign might get ugly in the long run-up to the Pennsylvania vote. “I just hope the two candidates don’t bash each other over the head for the next few weeks,” he said. “That’s the worst possible scenario.”

Pennsylvania Sen. Robert P. Casey Jr. concurred: “Our voters will have no patience for nastiness.”

Meanwhile, Democratic leaders were mulling plans to have Michigan and Florida hold primary votes after Pennsylvania and other primaries are finished in order to give those voters a say in the tight race.

Reflecting on that possibility and the fickleness of superdelegates, Cleaver said, “If another country elected leaders the way we do, we’d ask them to bring in the U.N. monitors.”